A conventional security inspection apparatus generally uses an X-ray source to emit X-ray radiation through an item to be inspected, so as to observe whether or not the item carries a suspected article. The item to be inspected is inspected by passing it through an inspection passage. However, a conventional inspection passage is designed such that the X-ray radiation may leak out from entrance and exit of the inspection passage and thus a person who takes his or her item near the entrance and exit will be irradiated by the X-ray radiation. As the X-ray radiation can seriously harm a human body, in order to avoid X-ray radiation leaking out from the inspection passage so as to harm a human body, a shielding structure is provided at, for example, the entrance and exit of the conventional inspection passage to block the X-ray radiation.